Feature ArticleNext-Generation Ocean Dry Mate Connector
By Dave Jenkins
There are fundamentally two different types of connectors available in the underwater arena for physical connections: wet mateable and dry mateable connectors. Wet mateable connectors can be connected while underwater. Dry mateable, or dry mate connectors, on the other hand, are connected (mated) above the waterline, and then the connector and cable assembly, and related equipment, are taken into the ocean environment.
The Elite Dry Mate Connector.
AMETEK SCP has accomplished a thorough review of industry specifications for the design of dry mate connections, to ensure that a product would be developed consistent with these specifications. The resulting innovative new connector also has a number of attributes that represent a leap forward in technology.
History of Dry Mate Connectors
The dry mate connectors offered today are much the same in configuration as the first connectors offered in the post-World War arena. Since that time, much has been learned about dry mate applications. Although the original designs were attached to system cables with an overmolding process, more recent designs have been adapted to pressure-balanced, oil-filled (PBOF) systems. In fact, one of the more widely used specifications for connectors and cabling systems for the oil and gas arena (Statoil TR2390) requires the use of PBOF cabling.
One might ask why the energy community would specify PBOF hoses instead of hard cable for its subsea connectivity hardware. The rationale for this is that the oil and gas community believes that overmolded designs are not capable of a 25-year lifetime, as the overmolding process is understood to have a life of not much greater than about 10 to 12 years. PBOF cabling systems, on the other hand, can be fitted with reliable, purpose-built terminations, and are currently sourced for production control systems that require a 25-year design lifetime.
Technology Gap Assessment
Conducting a formal technology gap assessment before beginning a product development effort is a proven way to ensure that you are indeed embarking on a project that will satisfy an existing market requirement. In the ocean equipment business, like any other business, in order to remain viable, the manufacturer must deliver what the customer is asking for, i.e., that which has a market. A 'really clever device' will remain just a 'really clever device,' unless there is a market for it.
Conducting a technology gap assessment ensures that the new product being considered can 'map' to an existing market and will contribute to the revenue stream of the company.
The standard process for conducting a technology gap assessment includes these general steps: studying the market and determining what is being asked for and where the product can add real value; identifying all areas of technology available; identifying the gaps between where we are today and where we want to be; and encouraging/developing products that close the technology gap and introduce the desired product.
AMETEK has conducted a technology gap assessment, resulting in a dry mate connector compliant with industry specifications and current design needs. Accordingly, the connector was evaluated for commercial risk and return, with the results being favorable at this time to introduce such a product.
The design effort that supports a new product should come from both a technology gap assessment and a requirements analysis. Currently available dry mate connectors were found to fall short of full compliance to application specifications.
AMETEK SCP has developed a dry mate connector that is compliant with these industry standards, and includes a number of enhancements that will be welcome to users of dry mate connectors.
From a requirements point of view, a new dry mate product would logically be designed to accommodate all available existing specifications, if at all possible. Relevant industry specifications that were examined included Mil-C-24231, API 16A Specification For Drill Through Equipment, API 16D Specification for Control Systems For Drilling Well Control Equipment and Control Systems for Diverter Equipment, API 17E Specifications for Subsea Umbilicals, ISO 13628-6 Petroleum and Natural Gas Industries, Design and Operation of Subsea Production Systems, Part 6: Subsea Production Control Systems, and STATOIL TR2390 Electrical/Optical Connectors and Jumpers for Subsea Control Systems.
Failure Mode Effects And Criticality Analysis
An additional activity that is extremely valuable in terms of reliability is to conduct a failure mode effect and criticality analysis (FMECA). A thorough FMECA is an essential part of requirements analysis. The analysis that was conducted follows the methodology as described in both MIL-STD-1629A and API 17N: Recommended Practice for Subsea Production System Reliability and Technical Risk Management.
In mechanical design, the essence of an FMECA is to examine all failure modes and to mitigate both their likelihood as well as their impact should they occur. In the parlance of the MIL-STD-1629A, probability ranges from frequent to extremely unlikely, and the consequences range from minor to catastrophic.
Note that in a new design, when specific parts configuration or failure data rate are not yet available, a qualitative approach is utilized. Failure modes identified in the FMECA are assessed in terms of grouped categories. Thus, the FMECA analysis of failure modes for both plug and receptacle included the following: main shell assembly, coupling ring (plug), electrical contacts and optical contacts.
The value of an FMECA during the design phase is that if done effectively, failure modes can be identified and then mitigated with thoughtful design. Therefore, a more reliable product can be developed and offered to the market. All possible failure modes for key components were identified, and then examined for probability of occurrence as well as impact. An example of the value of this analysis is a design choice that incorporates two seals to each point of seawater entry. Although many connector manufacturers might claim that in some cases one seal might be good enough, it is also true that O-rings can be damaged during assembly, fall out of position or extrude at high pressures. For these reasons, a second seal serves as a backup and can mitigate the effects of issues with one seal. The result of the FMECA analysis on the new dry mate connector allowed the designer to anticipate trouble areas, with an eye on all of the industry common failure modes. To continue this article please click here.
Dave Jenkins, P.E., M.S.M.E., M.A. is the vice president of business development at AMETEK SCP. He has more than 35 years of experience in oceanographic and subsea equipment and systems from the U.S. Navy and commercial oceanography. Jenkins has held leadership positions in program management, business development and operations at Ocean Design, Northrop Grumman, DRS and SEA CON.